test: add null primary key rejection tests for SQLite and PostgreSQL

Verify that INSERT operations with NULL primary key values are rejected
with an appropriate error message, even when the column lacks an explicit
NOT NULL constraint.

Author: andinux

test/postgresql/30_null_prikey_insert.sql

@@ -0,0 +1,68 @@
+-- Test: NULL Primary Key Insert Rejection
+-- Verifies that inserting a NULL primary key into a cloudsync-enabled table fails
+-- and that the metatable only contains rows for valid inserts.
+
+\set testid '30'
+\ir helper_test_init.sql
+
+\connect postgres
+\ir helper_psql_conn_setup.sql
+
+-- Cleanup and create test database
+DROP DATABASE IF EXISTS cloudsync_test_30;
+CREATE DATABASE cloudsync_test_30;
+
+\connect cloudsync_test_30
+\ir helper_psql_conn_setup.sql
+CREATE EXTENSION IF NOT EXISTS cloudsync;
+
+-- Create table with primary key and init cloudsync
+CREATE TABLE t_null_pk (
+    id TEXT NOT NULL PRIMARY KEY,
+    value TEXT
+);
+
+SELECT cloudsync_init('t_null_pk', 'CLS', true) AS _init \gset
+
+-- Test 1: INSERT with NULL primary key should fail
+DO $$
+BEGIN
+    INSERT INTO t_null_pk (id, value) VALUES (NULL, 'test');
+    RAISE EXCEPTION 'INSERT with NULL PK should have failed';
+EXCEPTION WHEN not_null_violation THEN
+    -- Expected
+END $$;
+
+SELECT (COUNT(*) = 0) AS null_pk_rejected FROM t_null_pk \gset
+\if :null_pk_rejected
+\echo [PASS] (:testid) NULL PK insert rejected
+\else
+\echo [FAIL] (:testid) NULL PK insert was not rejected
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Test 2: INSERT with valid (non-NULL) primary key should succeed
+INSERT INTO t_null_pk (id, value) VALUES ('valid_id', 'test');
+
+SELECT (COUNT(*) = 1) AS valid_insert_ok FROM t_null_pk WHERE id = 'valid_id' \gset
+\if :valid_insert_ok
+\echo [PASS] (:testid) Valid PK insert succeeded
+\else
+\echo [FAIL] (:testid) Valid PK insert failed
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Test 3: Metatable should have exactly 1 row (from the valid insert only)
+SELECT (COUNT(*) = 1) AS meta_row_ok FROM t_null_pk_cloudsync \gset
+\if :meta_row_ok
+\echo [PASS] (:testid) Metatable has exactly 1 row
+\else
+\echo [FAIL] (:testid) Metatable row count mismatch
+SELECT (:fail::int + 1) AS fail \gset
+\endif
+
+-- Cleanup
+\ir helper_test_cleanup.sql
+\if :should_cleanup
+DROP DATABASE IF EXISTS cloudsync_test_30;
+\endif

test/postgresql/full_test.sql

@@ -37,6 +37,7 @@
 \ir 27_rls_batch_merge.sql
 \ir 28_db_version_tracking.sql
 \ir 29_rls_multicol.sql
+\ir 30_null_prikey_insert.sql
 
 -- 'Test summary'
 \echo '\nTest summary:'

test/unit.c

@@ -2017,6 +2017,43 @@ bool do_test_error_cases (sqlite3 *db) {
     return true;
 }
 
+bool do_test_null_prikey_insert (sqlite3 *db) {
+    // Create a table with a primary key that allows NULL (no NOT NULL constraint)
+    const char *sql = "CREATE TABLE IF NOT EXISTS t_null_pk (id TEXT PRIMARY KEY, value TEXT);"
+                      "SELECT cloudsync_init('t_null_pk');";
+    int rc = sqlite3_exec(db, sql, NULL, NULL, NULL);
+    if (rc != SQLITE_OK) return false;
+
+    // Attempt to insert a row with NULL primary key — should fail
+    char *errmsg = NULL;
+    sql = "INSERT INTO t_null_pk (id, value) VALUES (NULL, 'test');";
+    rc = sqlite3_exec(db, sql, NULL, NULL, &errmsg);
+    if (rc == SQLITE_OK) return false;  // should have failed
+    if (!errmsg) return false;
+
+    // Verify the error message matches the expected format
+    const char *expected = "Insert aborted because primary key in table t_null_pk contains NULL values.";
+    bool match = (strcmp(errmsg, expected) == 0);
+    sqlite3_free(errmsg);
+    if (!match) return false;
+
+    // Verify that a non-NULL primary key insert succeeds
+    sql = "INSERT INTO t_null_pk (id, value) VALUES ('valid_id', 'test');";
+    rc = sqlite3_exec(db, sql, NULL, NULL, NULL);
+    if (rc != SQLITE_OK) return false;
+
+    // Verify the metatable has exactly 1 row (only the valid insert)
+    sqlite3_stmt *stmt = NULL;
+    rc = sqlite3_prepare_v2(db, "SELECT COUNT(*) FROM t_null_pk_cloudsync;", -1, &stmt, NULL);
+    if (rc != SQLITE_OK) return false;
+    if (sqlite3_step(stmt) != SQLITE_ROW) { sqlite3_finalize(stmt); return false; }
+    int count = sqlite3_column_int(stmt, 0);
+    sqlite3_finalize(stmt);
+    if (count != 1) return false;
+
+    return true;
+}
+
 bool do_test_internal_functions (void) {
     sqlite3 *db = NULL;
     sqlite3_stmt *vm = NULL;
@@ -7842,6 +7879,7 @@ int main (int argc, const char * argv[]) {
     result += test_report("DBUtils Test:", do_test_dbutils());
     result += test_report("Minor Test:", do_test_others(db));
     result += test_report("Test Error Cases:", do_test_error_cases(db));
+    result += test_report("Null PK Insert Test:", do_test_null_prikey_insert(db));
     result += test_report("Test Single PK:", do_test_single_pk(print_result));
 
     int test_mask = TEST_INSERT | TEST_UPDATE | TEST_DELETE;